Apparatus for separating suspended particles from gaseous bodies.



F. G. GOTTRELL & H. A. BURNS. APPARATUS FOR SEPARATING SUSPENDEDPARTIGLBS \FROM GASEOUS BODIES. APPLICATION FILED SEPT. 9, 1909. RENEWED3111.29, 1912. 1,035,422. Patented Aug. 13, 1912 2 SHEETS-SHEET 1.

F. G. GOTTRELL & H. A. BURNS. APPARATUS FOR SEPARATING SUSPENDEDPARTICLES FROM GASEOUS BODIES.

APPLICATION FILED SEPT. 9, 1909. RENEWED JAN. 29, 1912.

Patented Aug. 13, 1912.

2 SHEETS-SHEET 2.

UNITED STATES PATENT OFFICE.

FREDERICK GARDNER COTTRELL, 0F BERKELEY, AND HERBERT ALEXANDER BURNS,

OF OAKLAND, CALIFORNIA, ASSIGNORS TO INTERNATIONAL PRECIPITATING COM-PANY, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF CALIFORNIA.

APPARATUS FOR SEPARATING SUSPENDED PARTICLES FROM GASEOUS BODIES.

Specification of Letters Patent.

Patented Aug. 13,1912.

Application filed September 9, 1909, Serial No. 516,951. Renewed January29, 1912. Serial No. 674,199.

To all whom it may concern Be it known that we, Ennnnniox GARDNERCo'r'rnELL and HERBERT ALEXANDER BURNS, citizens ofthe United States,residing the said Co'r'rRELL at Berkeley, in the county of Alameda andState of California, and the said BURNS at Oakland, Alameda count-y,California, have invented certain new and useful Improvements inApparatus for Separating Suspended Particles from Gaseous Bodies, ofwhich the following is a specification.

Our invention relates to the class of apparatus for separating suspendedparticles from gaseous bodies by the application of electric charges;and it consists in the novel structure and arrangementof the electrodes,together with their supports and insulation, which we shall hereinafterfully describe and claim.

It is well known that the particles'of a gaseous body tend to depositfrom the latter when the gaseous body is brought within the fieldproduced by the juxtaposition of two bodies charged to a high electricpotential relatively to each other.

The term gaseous body as above and hereinafter used'is to be understoodas including all gases or vapors together with any solid or liquidarticles held in suspension therein. It is a so well known that suchdeposition of suspended particles from gaseous bodies is facilitated ifthe terminal bodies of the electric field, in which the gaseous body isinclosed, are of the nature of sharp points, sharp edges, fine hairs orother similar bodies of very small electric discharge surface. This isparticularly noticeable if the terminal bodies have pubescent surfaces.Such bodies holding, in any form, sharp points, sharp edges, fine hairs,pubescent surfaces, or other very small electric discharge surfaces,will be briefly referred to hereinafter as discharge electrodes, incontradistinction to collecting electrodes,. as defined below, wheresuch bodies are designed for terminals of an electric field. 1

When the two terminal electrodes of an electric field are, the one adischarge electrode and the other an electrode of smooth surface,relatively large in area com ared to the discharge surface of the 1 discarge electrode, the suspended particles .tend to deposit mainly upon thesmooth elec-' trode. This is especially noticeable where the field is ofessentially constant polarity, which latter term, is to be understood toinclude such alternating fields as have a higher voltage-during thealternations of one sign than during those of opposite sign, or suchreversals as are sufliciently infrequent to not interfere with thedeposition of individual particles of the gaseous body,

The above described smooth terminal may be conveniently called acollecting electrode and this term will be so'Lused herein.

One great difiiculty experienced in ap plying on a commercial scale thismethod of separating suspended particles from gas eous bodies, has beenthat of finding a suitable discharge electrode; and further difficultieshave been met in so arranging.

and supporting the electrode system, as to secure a uniform, rapid, andcomplete separation of suspende particles from gases moving withconsiderable velocity through a flue or chamber. To the overcoming ofthese difiiculties the following improvements are directed. Acommercially practical dis-- charge electrode should present to the gasa great extent of the finest possible points or edges. Furthermore 'itmust be highly resistant to any deteriorating action of the gaseousbody, as through chemical action of any of the constituents of thegaseous body, or high temperature of the latter. The materialscomprising the elect-rode, too, must be sulficiently non-inflammable, asWell as'heat resist-ant that any occasional arcing or sparking betweenthe electrodes, does not injure them. The electrode must necessarily bea sufficiently good conduct-or for the electric charge imposed upon it,and must be strong and rigid enough to allow its support n suchwise thatits required electrical insulat-ion may be maintained withoutdifficulty.

For a discharge material or element of-such an electrode, we have foundthat sheet; mica,

either in its natural form, or as manufac-- tured into its variousproducts, such as micanite, micabestos, etc., serves efiiciently and iseminently suitable for the purpose,

Hereinafter, for convenience, all such forms of sheet mica, natural ormanufactured into such products as micanite, micabestos, etc., will bereferred to as mica and where l l d mica is used, it is to beunderstood, as including all such forms, the term composite micaindicating such above mentioned manufactured forms.

The laminated structure of mica permits the opposing of a sharp,extremely thin edge to a collecting electrode, in such manner that astrong electric discharge may occur from the mica'edge. It has, also,the qualifications, that it is extremely resistant to ordinarychemicals, is not affected b moderately high temperatures, is non-inammable, and is not materially afiected' by such occasional disruptivedischarges as may occur between the electrodes. This permits its use incommercial plants, such as smelt ers, etc., where the gaseous bodies tobe treated have such constituent-s as sulfuric acid, highlydeteriorating to most available discharge materials, or where it may be.desired to treat the gaseous body at high temperatures. Being in itselfa non-conductor of electric charges with too little surface leakage fora sufficient conductance of such charges over a great length, and beingalso insufficiently strong and rigid to support-itself properly-as anelectrode, we have adopted the device of clamping the mica sheetsbetween supporting structures which are electrical conductors in suchmanner that the relatively narrow protruding mica edges may besufficiently charged through surface leakage over the mica from thecharges im-- posed upon the supporting structure.

W'here considerable mica edge is to be opposed to a corresponding lengthof surface of a collecting electrode with uniform free gas space, as arule, the mica will be made into' convenient strips and clamped betweenrods or bars, but such forms it is to be ununderstood, are determined bythe existing CO{I1dltlOIlS. 1 i

f the mica edge, in the above described discharge electrode be serrated,so that a series of pointed edges of the mica replace the continuousedge, the efliciency of the electrode is increased. When manufacturedforms of mica'as micanite, micabestos, etc., are used, the efliciency ofthe electrode is vincreased, if, after clamping the mica between itssupports, the cementing substance of the protruding edges is burned awayor otherwise removed from between the layers. By this means the finerlaminae of the mica are separated from one another, allowing each laminato have its discharge effect with less interference from charges uponadjacent laminae.

Referring now to the accompanying drawings:Figure 1 is a face elevationof -oneform of a discharge electrode. Fig. 2 .is an edge View of thesame. Fig. 3 1s a View showing the assemblage, in one form,

of the discharge electrodes and the collect 'ing electrodes. Fig. 4 is aview showing another form of assembling them. Fig. 5 isa view showing athird form of assemblage. Fig. 6 is a view showing still another form,together with features of sup port and insulation. Fig. 7 is a detail ofan insulation. Fig. 8 is a further detail of insulation. Fig. 9 is aview of the blank from which the top supports or hangers for thecollecting electrodes may be formed.

Considering first, Figs. 1 and 2, thedischarge electrode which wedesignate generally by B, is composed of the mica strip 1, clampedbetween two half round iron rods 2, one of which has formed at its topan eye 3 by which the electrode is suspended, and the other terminatesshort and has its top squared as seen in Fig. 2, to form a stop againstthe support from which the electrode is hung. The mica sheet 1,protrudes from the rods 2 and has its edgesfinely serrated. When thiselectrode is to be used in a flue in which H SO is the chief chemicalconstituent from which the electrode is to be protected, the iron rods 2may be protected by lead, the iron being for rigidity and the leadcoating for chemical protection from the sulfuric acid. ,{In practicaltreatment of gaseous bodies passing through fiues or chambers, the usualmethod employed is to arrange the electrodes in the fine or chamber sothat thegeneral direction of the force of the fields excited is at rightangles to thedirection of flow of the gas. Thus, in Fig. 3, the arrowshows the direction of flow of the gas through the flue 4:. A are thecollecting electrodes and B the discharge electrodes, for exciting thefields through which the gas mustflow.

l/Vhen the velocity of the gaseous body under treatment is high, and oneset of electrodes, as in Fig. 3 is not sufficient to remove all thesuspended particlesfrom the Fig. 4, wherein several discharge electrodesB are supported between wide collectingelectrodes A so that severalsuccessive electric fields may be excited in a direction at right anglesto the flo-w of the gaseous body, will often accomplish the desiredeffect. In

practice. however, the number of discharge electrodes to be so placedbetween the collecting electrodes is limited by mechanical difficulties,and for the higher velocities, an arrangement as shown in Fig. 5,has'proven more satisfactory. In this arrangement severalsets or rows ofelectrodes and B are placed in series. The number of such successivesets is limited only bfy the'length of flue or chamber available r thepm pose. 1 V e have also found that if the electrodes "are arranged asin Fig. 4,.the field first acting upon the gaseous body or portionthereof, is more efficientthan succeeding fields; that is, where severaldischarge electrodes are successively placed between two parallelcollecting electrodes, the several fields established .when theelectrodes are charged, are not equally efiicient in cleaning the gasflowing through them, the field first acting upon the gas being moreeffective than any of the succeeding fields. We have ,further determinedthat whenthe electrodes are arranged asin Fig. 6, successive fields aremore nearly if not quiteequal in efliciencyto that of the fields firstacting upon the gaseous body. Such an arrangement will be hereinafter.referred to as staggered. A st-aggered system may be described asfollowsz-When a series offields are established across thepath of agaseous body, in such wise that the gaseous body is successively actedupon by each field, the field electrodes are staggered if in the generaldirection .of flow of the gaseous body, they are laterally displacedwith respect-to it-he electrodes .of their own type,

which immediately precede them in the electrode system.

In Fig. '6 is shown, in detail, one type of staggered system,telectrodes, designed for removingsuspended particles fromgaseousbodics, flowing through horizontal flues oi'lchambers. Thecollecting electrodes A are suspended varallel to the directionof flowof gaseous body, from supports 5 which may be of any structural materialadapted for this purpose. These supports 5 may be held in arious waysdepen'dent upon the conditions met with in the structure of the flue orchamber. .At vthebottom end of the collecting-electrodes, a guide 6 ventswinging of theplates.

At their top ends the collecting electrodes terminate 111 hangers '7,which, opposite the discharge electrode B, should be, at most, butlittle thicker than the collecting electrode in order not'to reduce thefree gas spacing between the electrodes. The form shown is made of tinnest metal consistent-with the weight to b supportedandcons'ists of anoblong strip of metal, as shown in Fig. 9, doubled along the center ofthe strip, and-cut near the con ners which are turned up asseen in Fig.6 to I form the-bearing flanges. Where the collecting electrodes usuallythe case, must, necessarily, be electricall and for eflicient service insuch wise that every maintained at a fixed distance from the opposedcollecting electrode, this fixed distance to be the same for alldischarige electrodesof this system. As the nature 0 gaseousbodiescommonly found in commercial plants, prohibits the supporting of suchinsulator'with- 'in the limits of thegaseous bod suitable supports mustbe provided-outsi e the flue or chamber confining the gaseous body,

wherethe insulation may be kept clear and boundaries. i

serves to pre-- 'lators 9 outside of the flue.

are? to be grounded, as is, the discharge electrodes insulated;

discharge terminal of the electrode is For this purpose the bus bars 8(Fig. 6) restino upon the insulators 9 must pass through holes in thewalls of the flue or chamber, these holes to be sufiiciently large toallow clearance between the bus bar and wall so that there will be noelectrical'arcing or shorting at this point. -When.such holes interferewith the working draft, they must be closed without injuring the bus barinsulation. This may be done as shown in of terminals as is indicated inFig. 6,

10 is a tube covering the hole outside the flue, said tube being ofmaterial dependent upon conditions at the flue and concentric or nearlyso with axis of the bus bar 8, passing through the hole. The outeropening of the tube isclosed by adisk or cone-11 of any suitableinsulating material, such' as mica, glass, etc., which fits snuglyaround the bus bar and closely against the tube.'

\Vhenthe gaseous body is di'y, o-r the draft of. the flue sufiicientlyhigh, a few small holes in the insulating disk or cone llefitdlnltsuflicient air from the outside, to prevent any of the gaseous bodydepositing upon the insulation. In many cases, however, where portionsof the gaseous body may deposit upon the insulating disk or cone,suspended particles ing tube 10 by the device shown in Fig.-8, whereinthe inner end of the tube 10 is seen, and B is a discharge electrodefitted around the bus bar 8, outside the lineof the flue wall, thusslightly within the tubes The inner end of the tube thus beco-mes'acollecting electrode opposed to discharge electrode B, and the fieldestab-' lished ,tends to keep tlieouter end of the tube free from allsuspended particles. In Fig. 6 isshown discharge electrode B, keyed orotherwise fastened to bus bars 12 securely at the top. This method hasproved entirely satisfactory. These bars 12 in turn are supported bybars 13 which run parallel to the flue walls. The bars 13 may be heldupon horizontal bars 8,. which pass through the side walls of the flueand rest upon insu- In Fig. 6, 14 represents a prevent the gas passingbehind the collect-- 111g electrode A resting against it, this space beng too narrow to admit a discharge electrode A. The dead space filled byblock 14 occurs by virtue of the staggered arrangement in each row ofelectrodes, and with consecutive rows is alternately at opposite sidesof the flue. 7

Having thus described our invention what we claim as new and desiretosecure by Letters Patent is 1. In an a paratus for separatin sus;pended partic es from gaseous bodies by application of electric charges,discharge e ectrodes consisting .of mica sheets secured therein areprevented from enter-' bafiling block to the to an electricallyconductive supporting 13 of plates, serving as structure in such wisethat the mica edges protrude'from the supporting structure.

2. In an apparatus for separating suspended particles from gaseousbodies by the application of electric charges, discharge electrodesconsisting. of mica sheets with serrated edges, secured to anelectrically conductive supporting structure, in such wise that the micaserrations protrude from the supporting structure.

3. In an apparatus for separating ,sus-

pended particles from gaseous bodies by the application of electriccharges, discharge electrodes composed of mica sheets secured to anelectrically conductive supporting structure in such wise that the micaedges protrude from the supporting structure, in combination withcollecting electrodes opposed to said discharge electrodes as terminalsof an electric field. 4. In an apparatus for separating suspendedparticles from gaseous bodies by the application .of electric charges,discharge electrodes consisting of mica sheets with serrated edges,secured to an electrically conductive supporting structure, in such wisethat the mica serrations protrude from the supporting structure, incombination with collecting electrodes opposed to said dischargeelectrodes as terminals of an electric fiel I 5. In an apparatus forseparating suspended particles from gaseous bodies by the application ofelectric charges, discharge electrodes consisting of composite micasheets secured to an electrically conductive supporting structure insuch wise that the mica edges protrude from the supporting structures,the cementing substance of said mica sheet being removed from itsprotruding edges.

- 6. In an apparatus for separating suspended particlesfrom gaseousbodies by the application of electric charges,- a plurality arranged atequal intervals from one another in successive rows across thegascarrying flue, the plane of each individual plate being substantiallyparallel to the dicollecting electrodes,

I rection of. travel ofthe gases and the succes sive rows of platesbeing disposed lengthwise of the flue, the plates in each row beingopposite the spaces between the plates of the adjacent rows, anddischarge electrodes situated between each pair of collecting electrodesin the individual rows.

7. In an apparatus for separating suspended particles from gaseousbodies byv the application of electric charges, the combination of asystem of field electrodes in a flue or chamber through which thegaseous body flows; a supporting conductive frame for said. electrodes,part of'said frame passing outwardly through an opening in the flueorchamber wall, and supported exteriorly upon electric insulators, andmeans for insulating said outwardly extending part in its,

wall opening consisting of a tube fitting and passing through theopening, and freely surrounding said extending part, and an insulatingcover for the outer end of said tube.

8. In an apparatus for separating suspended particles from gaseousbodies by the application of electric charges, the combination of asystem of field electrodes in'a flue or chamber through which thegaseous body flows; a supporting conductive frame for said electrodes,part of said frame passing outwardly through an opening in the flue orchamber wall, and supported exteriorly upon electric insulators, andmeans for insu lating said outwardly extending partlin its wall openingconsisting of a tube fitting and passing through the opening, and freelysurrounding said extending part and a discharge electrode fittedon theframe inside the opening and forming with the opposing inner end of thetube an electric field.

In testimony whereof we have signed our names to this specificationinthe presence of two subscribing witnesses.

FREDERICK GARDNER COTTRELL. HERBERT ALEXANDER BURNS.

Witnesses:

WM. F. BOOTH, D. B. RICHARDS.

